$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gdk4.git /var/lib/mock/f40-build-1780565-24818/root/chroot_tmpdir/scmroot/rubygem-gdk4
Cloning into '/var/lib/mock/f40-build-1780565-24818/root/chroot_tmpdir/scmroot/rubygem-gdk4'...
$ git fetch origin 2d2dd0f84aae2f53cd4b10455ef7d9657d12b081:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gdk4
 * [new ref]         2d2dd0f84aae2f53cd4b10455ef7d9657d12b081 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2d2dd0f 4.2.2 entry